Dietary protein chemical score

The quality of different proteins can be expressed according to their chemical score, protein efficiency ratio (PER), biological value (BV), and net protein utilization (NPU). These parameters refer to the different tests used to define the protein s quality. The chemical score refers only to the property of the protein in question. The PER, BV, and NPU refer to relationship.s between the dietary protein and the consumer. The values of the PER, BV, and NPU depend on properties of both the protein in question and the needs of the animal. The chemical score, PER, BV, and NPU of proteins in various foods, including eggs, fish, rice, and maize, are listed in Table 8,1 3. 

Dietary protein for growing pigs can also be expressed in the form of ideal protein. This is a modification of the chemical score. If the main limiting amino acid is lysine at 50 g/kg CP, then if we use the recommended content of lysine in the ideal protein of 70 g/kg CP, the score would be 50/70 = 0.70 and the ideal protein content would be 700 g/kg CP. A diet with 170 g/kg of this protein would then supply 170 X 0.7 = 119 g ideal protein/kg. Requirements are usually stated in terms of apparently digested ideal protein (ADIP) and a digestibility of 0.75 is assumed in transforming the ideal protein supply to an ADIP supply. 

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